The present invention relates to reluctance motors and, more particularly, to variable reluctance stepper motors.
A reluctance motor makes use of the dependence on position of energy in a magnetic circuit to develop mechanical force in the direction of least reluctance. A magnetic circuit provides a path for magnetic flux in much the same way that an electrical circuit provides a path for electrical current. Just as electrical current follows the path of least resistance, magnetic flux follows the path of least reluctance.
One known variable reluctance stepper motor employs a toothed rotor/stator combination in which rotation of the rotor causes a cyclic variation in the reluctance of the magnetic circuit, which includes the rotor and stator teeth and the gap therebetween. The gap changes dimension as the rotor and stator move relative to one another. A motor capable of providing continuous stepping motion is comprised of two or more such sets of rotor/stator teeth, as well as separate magnetic circuits extending therethrough, which circuits are capable of being selectively energized. The different rotor/stator teeth are staggered in relative angular positions. By selective energization of the magnetic circuits, the rotor is caused to assume successive positions of least reluctance for the respective magnetic circuits, depending on the magnetic and mechanical variables designed into the motor and the method of control. In conventional variable reluctance stepper motors, the rotor and stator teeth are of the same or nearly the same width. This configuration produces the greatest possible difference between maximum and minimum reluctance.